I’m am assuming that you had internet in the livecd since you said you completed installation? That’s strange for it not to carry over but nothing serious. If you chose GNOME, Xfce, or Openbox you can enable and then reset your network connection with:

Also @Freecaster, you may from time-to-time need to find a package with a certain name, or partial name. To do this, you can use the command:

pacman -Ss connman

Which, for example, should give you this listing:
community/connman 1.19-1
Wireless LAN network manager
antergos/qconnman 20130512-1
A Qt ConnMan management interface.
antergos/qconnman-ui 20130512-1 <== As you can see, this is the one you were having trouble finding.
A Qt ConnMan UI management interface.

However, if you wish to also check in the AUR, and you have ‘packer’ installed, you can use: